Addressing Unfeasibilities of Energy Storage Systems Participating in Energy and Reserve Markets.

Optimization algorithms formulated to define the joint participation of Energy Storage Systems (ESSs) in energy and reserve markets often lead to unfeasibilities related to the available energy stored in the ESS, particularly if a relatively long-time horizon is considered (e.g., 24 hours). This paper addresses this issue and proposes an ESS model that assigns a specific amount of energy for up or down reserve provision according to the needs of ESS operator. Generally, ESSs do not participate on their own in the aforementioned markets, but rather, they usually operate jointly with stochastic non-dispatchable Renewable Energy Sources (RESs) in the form of a Virtual Power Plant (VPP). The proposed model allows operators to avoid possible unfeasibilities, and the potential penalties resulting from deviating from the day-ahead market (DAM) and secondary reserve market (SRM) offers. The model is implemented for a VPP consisting of a wind farm, a solar PV plant, and an ESS. The effectiveness of the model for bidding in joint markets is validated by several case studies.